Carbonated drinks sealed in cans or bottles can absolutely rupture when exposed to high temperatures, and the physics behind it is straightforward. The carbon dioxide dissolved in the liquid becomes less soluble as the beverage warms, forcing more gas out of solution and into the headspace of a sealed container. At the same time, the liquid itself expands. Both of these effects raise the internal pressure, and if the container can’t hold that pressure, it fails. Whether that failure is a quiet leak along a seam or a dramatic burst depends on the container, the temperature, and how quickly the heat builds.
What Happens Inside a Sealed Can as It Heats Up
A sealed carbonated drink is a pressurized system. At a comfortable room temperature, the carbon dioxide dissolved in the liquid and the CO2 gas in the small air pocket above the liquid surface sit in a rough equilibrium. Heat disrupts that balance in two ways. First, gas solubility in liquid drops as temperature climbs. Carbon dioxide that was happily dissolved at 20°C starts escaping into the gas phase at 35°C or 40°C. Second, the liquid itself takes up more space as it warms. In a rigid container that cannot flex much, even a small increase in liquid volume translates directly into higher pressure because there is nowhere for the expanding fluid to go.
These two forces compound each other. You get more gas pushing against the container walls and more liquid volume trying to occupy a space that hasn’t grown. Analytical models of liquid thermal expansion in closed vessels confirm that geometric constraints of the container and the initial state of the liquid both influence how fast pressure builds during wall-conducted heating.1Proceedings of the Mavlyutov Institute of Mechanics. Increase of liquid pressure in a closed volume due to thermal expansion during heating through walls In practical terms, a soda can sitting in a hot environment is a small pressure vessel steadily inflating from the inside.
How Much Pressure a Soda Can Handles
Aluminum beverage cans are engineered to hold internal pressures in the range of about 50 to 60 psi under normal conditions. That is already a meaningful amount of force. The thin aluminum walls experience a hoop stress of roughly 130 MPa at those pressures, which is close to 45 percent of the material’s yield stress. In other words, even at room temperature, the can is working at nearly half its structural limit.2Engineering Fracture Mechanics. A pressure vessel fracture mechanics study of the aluminum beverage can
During warm weather or what engineers call “severe service conditions,” internal pressure can climb to around 90 psi. At that point, the hoop stress reaches about 207 MPa, which is roughly 73 percent of the yield stress. The can hasn’t failed yet, but its safety margin has shrunk considerably.2Engineering Fracture Mechanics. A pressure vessel fracture mechanics study of the aluminum beverage can Add a small defect in the aluminum, a dent from handling, or a weakened seam from manufacturing variation, and you have the conditions for a rupture. The can doesn’t need to be heated to some extreme temperature to fail. It just needs enough pressure to exploit whatever flaw exists in the metal.
This is why the failures people encounter tend to be somewhat unpredictable. Two identical cans sitting side by side in the same hot trunk might behave differently. One might survive. The other might have a microscopic scratch near the rim from a six-pack ring that acts as a stress concentrator. At 90 psi, that scratch becomes the starting point for a crack, and the can vents or bursts.
The Parked Car Problem
The most common real-world scenario for soda explosions involves a vehicle parked in direct sunlight. Research on solar heating of vehicle cabins shows that the temperature inside a parked car can climb more than 20°C above the ambient outdoor temperature.3Sustainability. Investigation of the Effect of Solar Ventilation on the Cabin Temperature of Vehicles Parked under the Sun On a 35°C (95°F) summer day, that means the inside of your car can reach 55°C (131°F) or higher. The dashboard, which absorbs direct solar radiation through the windshield, can get significantly hotter than even the cabin air.
A can of soda sitting on the dashboard or in a cup holder is being heated not just by warm air but by radiant energy from every sun-heated surface surrounding it. The beverage inside doesn’t need to reach boiling temperature to become dangerous. At 55°C, the CO2 pressure inside the can has already risen well above what it was at room temperature. If the car was parked for several hours and the can had time to equilibrate with the cabin temperature, the pressure is at or near the danger zone.
Trunk storage is somewhat better because trunks don’t have the greenhouse effect of windows, but they still get very warm. A case of soda left in a trunk through a summer afternoon can easily warm to 45–50°C. That is enough to push some cans to the edge, particularly if they were shaken during the drive before being parked.
Glass Bottles Fail Differently
Aluminum cans are thin-walled and tend to fail along seams or at points of pre-existing damage. Glass bottles are rigid and brittle, which means they tend to fail catastrophically rather than leaking gradually. When a glass bottle of carbonated drink explodes, it produces sharp fragments traveling at speed, and the consequences can be serious.
A clinical case series from Nigeria documented eye injuries caused by exploding glass bottles of Coca-Cola. The study noted that subjecting carbonated bottled drinks to heat and agitation releases dissolved carbon dioxide and can increase internal pressure to dangerous levels. Several of the injuries occurred among traders who stored crated soft drinks outdoors in the sun and then brought them inside for refrigeration, handling and jostling the crates during the process.4PubMed Central. Ocular injuries from exploding glass-bottled Coca-Cola drinks in Port Harcourt, Nigeria The combination of solar heating and physical agitation during transport created the conditions for spontaneous rupture.
Glass bottles in many markets have been largely replaced by plastic PET bottles, which handle overpressure differently again. PET is flexible enough to deform outward before failing, which is why an overheated plastic bottle of soda often swells into a taut, rounded shape before it bursts. The failure, when it comes, is usually a spray of foam rather than a shower of sharp fragments. It’s still messy and startling, but far less likely to cause physical injury than an exploding glass bottle.
Why Shaking and Heat Together Are Especially Bad
Heat alone raises the pressure inside a sealed carbonated container, but agitation accelerates the process dramatically. When you shake a sealed bottle or can, you create turbulence that helps dissolved CO2 come out of solution faster. Instead of the gas slowly migrating to the headspace as the liquid warms, shaking generates countless tiny nucleation sites where bubbles can form all at once.
Research into the fluid dynamics of carbonated beverages has shown that physical disturbance triggers the formation of dense bubble clouds, with individual clouds containing about a million microbubbles. These clouds are far more effective at driving convective motion inside the bottle than individual bubbles would be. The resulting bubbly plumes promote mixing throughout the liquid and accelerate degassing.5Physics Today. The fluid mechanics of bubbly drinks In plain terms, the CO2 that was sitting quietly in the liquid gets stripped out fast, and the headspace pressure spikes.
This is why a warm, recently jostled can is far more dangerous than a warm can that has been sitting still for hours. A case of soda that bounced around in the back of a truck on a hot day and was then left in the sun combines both risk factors. The agitation during transport shakes CO2 out of solution, and the heat prevents it from redissolving. The pressure has nowhere to go but up.
Temperature Thresholds People Ask About
There is no single magic temperature at which every can of soda will explode. The failure point depends on the carbonation level, the specific beverage formulation, the container material, any existing flaws in the container, and how long the container stays at high temperature. That said, some rough guidelines help.
At normal refrigerator temperature, around 4°C (39°F), a typical soda can holds internal pressure well within its design range. At room temperature, roughly 20–22°C (68–72°F), the pressure is higher but still comfortably below the failure threshold. Once you get above about 40°C (104°F), things start getting marginal. The internal pressure is approaching the upper range of what the container was designed for. Above 50°C (122°F), which is easily reached inside a parked car on a summer day, you are in territory where a structurally perfect can might hold but a slightly damaged one might not.
Highly carbonated beverages like certain energy drinks or sparkling water brands start at higher baseline pressures and have less headroom before reaching the container’s limits. Sugar-free formulations and full-sugar formulations behave similarly in terms of pressure buildup since the carbonation level, not the sweetener, is the main variable driving gas-phase pressure.
Freezing Is the Other Thermal Extreme
While heat gets most of the attention in conversations about exploding soda, freezing is actually more reliable at destroying containers. Water expands by about 9 percent when it freezes, and since soda is mostly water, the same expansion happens. Unlike the gradual pressure buildup from heat, freezing creates a solid mass of expanding ice that has nowhere to go inside a rigid container. Cans split open, bottles crack, and the result is a frozen soda sculpture surrounded by shattered glass or peeled-back aluminum.
The mechanism is different from heat-driven failure. With heat, the failure comes from gas pressure. With freezing, the failure comes from the physical expansion of the liquid turning solid. Both get you the same end result: a ruined container and a mess. But freezing is more predictable because the expansion is large and unavoidable, whereas heat-driven failures depend more on the specific conditions and container integrity.
If you’ve ever put a can of soda in the freezer to chill it quickly and forgotten about it, you’ve probably seen the result. The can usually splits along a seam, and the frozen soda oozes out like a slow-motion eruption. It’s less dramatic than a heat explosion but arguably more reliably destructive.
Practical Steps to Avoid the Mess
If you regularly transport drinks in your car during warm months, a few habits help. Keeping cans and bottles in an insulated cooler bag, even without ice, slows the heating process considerably. The insulation buys time. If you can’t use a cooler, the floor of the back seat or the trunk is better than the dashboard or a sun-exposed seat. Floors stay cooler because they’re shielded from direct solar radiation.
When retrieving drinks that have been sitting in a hot car, handle them gently. A warm can that hasn’t been disturbed has had time for its internal pressure to stabilize, with the CO2 reaching a new equilibrium at the higher temperature. Grabbing it roughly, dropping it into a cooler, or tossing it to someone reintroduces agitation on top of the already elevated pressure. Open warm cans slowly and pointed away from your face. The pressure release when you crack the tab on a hot can is noticeably more forceful than on a cold one, and a foam geyser is the likely greeting.
For long-term storage, keep beverages in a climate-controlled space. A garage that routinely exceeds 40°C in summer is not a good storage location for cases of soda. The cans probably won’t explode from a single hot day, but repeated thermal cycling weakens the container over time. The aluminum fatigues, seams soften, and eventually a can that survived twenty hot days fails on the twenty-first.
When Cans Bulge but Don’t Burst
Not every overheated can explodes. Many just swell. You may have noticed a can that looks subtly puffed out, with the normally concave bottom dome pushed outward so the can won’t sit flat anymore. That dome reversal is actually a useful warning sign. Beverage cans are designed with a concave bottom specifically because that shape resists internal pressure efficiently. When the pressure inside rises enough to push the dome outward, the can has exceeded its normal operating range.
A dome-reversed can hasn’t necessarily failed. The walls might still be holding fine. But it has been overpressurized at some point, and opening it will produce a more vigorous release than usual. The flip side is that if the dome has already popped outward and the can isn’t leaking, the container has demonstrated it can handle the current pressure. It’s the cans with existing flaws that tend to rupture before the dome even has a chance to reverse.
Commercially, dome reversal is a quality control issue. Beverage companies design their cans so that the dome reversal pressure is below the burst pressure. This creates a built-in warning: the can changes shape visibly before it reaches the point of catastrophic failure. If you see a swollen can, you know it’s been stressed. Whether you want to open it carefully or toss it is up to you, but don’t shake it first.
Does the Type of Carbonated Drink Matter?
All carbonated drinks share the same basic physics, but some are pressurized more aggressively than others. Club soda and seltzer water tend to have higher carbonation levels than colas, which means they start at a higher baseline pressure and have less margin before reaching container limits. Some craft sodas and imported sparkling waters are carbonated quite heavily and packaged in glass, a combination that makes them more prone to dramatic failure in heat.
Beer, which is also carbonated, follows the same principles but generally at lower pressures than most soft drinks. A can of lager left in a hot car will swell and potentially burst, but it’s starting from a lower pressure baseline, so it takes a bit more heat to push it over the edge. The exception is highly carbonated beer styles, where the carbonation level can rival or exceed that of soda.
Drinks bottled in champagne-style bottles with wire cages over the corks are already under significant pressure at room temperature. Leaving a bottle of sparkling wine in a hot car is asking for trouble. The cork can launch itself with enough force to crack a windshield, and the bottle itself can shatter. Unlike soda containers, which are at least designed for some thermal variation, champagne bottles assume they’ll be stored in cool cellars. They have very little tolerance for the kind of temperatures found inside a sun-baked vehicle.